Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Nat Mater. 2012 Jan 29;11(3):208-12. doi: 10.1038/nmat3230.
The integration of radiofrequency electronic methodologies on micro- as well as nanoscale platforms is crucial for information processing and data-storage technologies. In electronics, radiofrequency signals are controlled and manipulated by 'lumped' circuit elements, such as resistors, inductors and capacitors. In earlier work, we theoretically proposed that optical nanostructures, when properly designed and judiciously arranged, could behave as nanoscale lumped circuit elements--but at optical frequencies. Here, for the first time we experimentally demonstrate a two-dimensional optical nanocircuit at mid-infrared wavelengths. With the guidance of circuit theory, we design and fabricate arrays of Si3N4 nanorods with specific deep subwavelength cross-sections, quantitatively evaluate their equivalent impedance as lumped circuit elements in the mid-infrared regime, and by Fourier transform infrared spectroscopy show that these nanostructures can indeed function as two-dimensional optical lumped circuit elements. We further show that the connections among nanocircuit elements, in particular whether they are in series or in parallel combination, can be controlled by the polarization of impinging optical signals, realizing the notion of 'stereo-circuitry' in metatronics-metamaterials-inspired optical circuitry.
在信息处理和数据存储技术中，将射频电子方法集成到微纳尺度平台上是至关重要的。在电子学中，射频信号由“集总”电路元件（如电阻器、电感器和电容器）控制和操作。在早期的工作中，我们从理论上提出，经过适当设计和巧妙布置的光学纳米结构可以在光学频率下表现为纳米级集总电路元件。在这里，我们首次在中红外波长下实验证明了二维光学纳米电路。在电路理论的指导下，我们设计并制造了具有特定深亚波长横截面的 Si3N4 纳米棒阵列，在中红外区域定量评估了它们作为集总电路元件的等效阻抗，并通过傅里叶变换红外光谱证明这些纳米结构确实可以作为二维光学集总电路元件发挥作用。我们进一步表明，纳米电路元件之间的连接，特别是它们是串联还是并联组合，可以通过入射光信号的偏振来控制，从而在基于超材料启发的光学电路的“立体声电路”中实现了这一概念。
